Engine Coolant Temperature Sensor Out of Range
Indicates that the engine coolant temperature sensor is reading a value outside the expected range.
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What it means (plain English)
The engine coolant temperature sensor should sense and report the coolant temperature, typically between 180°F and 220°F (82°C to 104°C). If it reads higher than this range, say 250°F (121°C) or lower than 140°F (60°C), the computer sees this as a fault.
What the computer is actually seeing
The engine control module (ECM) is expecting a voltage signal from the coolant temperature sensor, typically around 0.5V (approximately 32°F / 0°C) to 4.5V (approximately 240°F / 115°C). Out-of-range values trigger this fault code.
What a healthy reading looks like
Coolant temperature between 180°F and 220°F (82°C to 104°C) should yield 1.25V to 2.5V from the sensor.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the coolant level in the reservoir. If low, top off and test. Decision: Is level okay? If no, replenish coolant, then retest for code.
- 22. Inspect wiring and connectors at the coolant temperature sensor for damage or corrosion. Decision: Is wiring intact? If no, repair as necessary, then retest for code.
- 33. Using a scan tool, read the coolant temperature data. Compare this reading to your actual coolant temperature (using an IR thermometer). Decision: Are readings within range? If no, replace the coolant temperature sensor and retest.
- 44. If the sensor is replaced and the code returns, check the ECM for updates or faults. Decision: Are any other fault codes present? If yes, troubleshoot those.
- 55. Ensure the thermostat is functioning properly. It should open around 195°F (91°C). If stuck closed, replace the thermostat.
Common causes
- Faulty coolant temperature sensor
- Corroded or damaged wiring
- Connector issues
- Low coolant level
- Thermostat stuck open or closed
Typical repair cost
$$ - $$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to address it soon as incorrect coolant temperature can affect engine performance and emissions.
Will this code come back after clearing?
If the underlying issue isn't fixed, the code will likely return.
Why might it pair with other codes?
Multiple codes can indicate a systemic problem such as electrical issues or sensor failures affecting multiple systems.
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